Most ornamental grasses will stay intact through the latter part of the year, providing useful colour and structure in the autumn, when herbaceous plants are dying back. Some are particularly vibrant, picking up on the colours of the trees to echo their shades of russet and yellow, but with lower, softer silhouettes and lots of movement. Using them is easy. Weave them into a herbaceous border, or create more impact in larger gardens by repeat planting, as Piet Oudolf did at Scampston Hall in North Yorkshire, with his sinuous banks of Molinia caerulea subsp. caerulea 'Poul Petersen'. Some grasses are deciduous while others are evergreen. It is the deciduous grasses that can dramatically change colour during the autumn.
Species and cultivars
Of the deciduous grasses, the panicums are always good value in autumn. P. virgatum 'Shenandoah' (1.2 metres) has red-tipped leaves that turn a spectacular deep burgundy, while 'Northwind' (1.5 metres) has blue-grey foliage that turns yellowy orange. Most cultivars of Miscanthus sinensis look good in autumn, with their distinctive plumes fading to silvery white as the season goes on, but possibly the best for autumn colour is 'Ferner Osten', with sprays of leaves that turn bright coppery red underneath buff brown plumes. The molinias or purple moor grasses are excellent in autumn, their leaves turning butter-yellow. 'Poul Petersen' forms strong clumps of upright stems up to 90cm, while 'Heidebraut' is slightly taller at 1.2 metres. A grass I am longing to try is the evergreen Chionochloa rubra (1 metre) from New Zealand, which produces distinctive, rounded clumps of delicate copper-brown foliage.
Panicum and miscanthus are warm-climate grasses that will thrive in full sun in a reasonably moist and fertile soil; they will also tolerate dry soils but won't grow as readily. Flowering late in the season, they will stay intact all winter and should be cut back in late winter or early spring to make way for new growth. The molinias are cool-climate grasses that also like a moisture-retentive soil and full sun. However, because they are European natives, they are more likely to survive an excessively wet winter. Chionochloa rubra, on the other hand, is trickier to please, and will not do well in heavy soils. Planting it in an open, sunny spot in a fertile, well-drained soil, will give it the best chance of survival.
This story was originally published on House & Garden UK.